It is known that, in the polymerization-in-emulsion processes, polymeric latexes are obtained which contain residual monomers from which polymers substantially free from said monomers are to be recovered.
It is known, too, that the conventional processes for removing the residual monomers from the polymeric latexes and for separating the polymers from said latexes exhibit several drawbacks deriving from the formation of foams, coagulums and foulings in general, which render difficult and expensive the running of the separation apparatuses and, above all, do not permit to attain, in an economic manner, low contents of residual monomers in the separated polymer.
Several methods have been suggested for removing residual monomers from polymeric latexes by distillation (stripping) in a vapor stream.
According to one of these methods, the latex is partially evaporated in a tray exchanger and then separated from the vapors in a column.
In order to reach low percentates of residual monomers, said operations are carried out in 2, 3 or more steps.
According to another method the residual monomers are removed by using thin layer centrifugal apparatuses.
Said methods involve the use of expensive and low-productive equipments, the operating and maintenance costs of which are very high.
Also, the recovery of the polymers from their latexes, which is usually effected by coagulation by means of proper coagulating agents such as CaCl.sub.2, Al.sub.2 (SO.sub.4).sub.3 and the like, exhibits some drawbacks due to the fact that it is necessary to employ large apparatuses, which run under onerous operating conditions owing to the forming of foulings and because it is necessary to remove, also, the coagulating agents introduced into the latex.